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  • 1
    Electronic Resource
    Electronic Resource
    The Accuracy in Microweighing in Vacuum and Controlled Environments (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 413-429 
    Details
    ISSN: 1572-8943
    Keywords: accuracy in microweighing in vacuum and controlled environments ; vacuum microbalance techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Accurate weighing depends on both physical factors and the weighing technique. There are two categories of physical factors: the location and support of the balance, and physical phenomena. Important such phenomena include processes of heat transfer by convection and radiation in rarefriction gases, Archimedes buoyancy, electrostatic, magnetostatic and gravitational effects, etc. Surveys of disturbances which affect the accuracy of weighing in vacuum or in controlled environments have been published elsewhere. This paper describes a high-vacuum apparatus connected to a Cahn RG ultramicrobalance. The system was adapted for investigations of long-time kinetic runs of oxygen loss in oxide superconductors in dynamic vacuum, and of other gas - solid interactions. Typical calibration curves for 'not fully compensated system' are presented in controlled environments at cryogenic temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010103315451
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal Decompositions of (RE)Ba2Cu3O6 (RE=Y, Nd, Er) (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 691-698 
    Details
    ISSN: 1572-8943
    Keywords: activation energy ; kinetics ; solid-state reactions ; superconductors ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetric in situ measurements of oxygen loss from (RE)Ba2Cu3O6 samples (RE=Y, Nd, Er) heated isothermally in a relatively high dynamic vacuum were made with a Cahn RG electrobalance. Single-phase orthorhombic samples of composition (RE)Ba2Cu3O7-x (highest oxygen content) were synthesized from stoichiometric (1:2:3) mixtures of high-purity (RE)2O3, BaCO3 and CuO. The original 1:2:3 mixture was prepared by the two-stage procedure described earlier. The crystal structure of the sample in the original orthorhombic phase was controlled by the X-ray powder method (CuKα radiation) using a Stadi P Stoe diffractometer with a position-sensitive detector. The decomposition curves are described by the sum of exponential terms corresponding to rapid and slow first-order processes in which differently sized grains of the powder samples are involved. The activation energies are estimated from appropriate Arrhenius plots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010182927688
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  • 3
    Electronic Resource
    Electronic Resource
    Microgravimetric Investigations of High-Temperature Superconductors (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 661-670 
    Details
    ISSN: 1572-8943
    Keywords: controlled environment ; high-Tc superconductors ; microgravimetric investigations ; oxide superconductors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It has been confirmed that, in oxide superconductors, the superconducting transition temperature Tc depends strongly on the oxygen content and oxygen ordering. The microgravimetric method is very useful in the analysis of oxide superconductors, because it allows investigations in vacuum and controlled environments in classical applications: thermogravimetric analysis, kinetics and thermodynamics of reaction, determination of oxygen contents in redox reactions, investigations of the correlation of the deviation from stoichiometry and carrier concentration and also the combined measurement of mass and additional parameters, e.g. evolved gas analysis, etc. Selected papers are reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010126809941
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  • 4
    Electronic Resource
    Electronic Resource
    Microbalance and Related Studies of High-temperature Superconductors (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 353-363 
    Details
    ISSN: 1572-8943
    Keywords: controlled environment ; high-T c superconductors ; kinetics ; microgravimetric investigations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Many properties of oxide superconductors depend on the oxygen concentration and its distribution in the samples. The microgravimetric method is very useful to study of oxide superconductors, as it allows investigations in vacuum and controlled environments in classical applications: thermogravimetric analysis for the study of solid-state reactions, determinations of oxygen contents in redox reactions and the combined measurement of mass and additional parameters, e.g. evolved gas analysis etc. Single-phase samples of high-temperature superconductors were synthesized from stoichiometric mixtures of high-purity oxides and carbonates. Appropriate amounts of the precursor powders were homogenized manually or by a mechanical ball mill and subsequently calcined at temperatures in the 800 to 950°C range with intermediate grinding to ensure homogenous reaction. The lattice parameters of all preparations were controlled, in both initial and final experiments, by the X-ray powder method (CuKα radiation), using a Stadi P (Stoe) diffractometer with a position-sensitive detector. It is well known that temperature and mass can be measured with an accuracy higher by orders of magnitude than it is still possible for the thermoanalyst to determine the transformation temperatures or the mass changes due to overlapping partial reactions. Applications of Cahn microbalance to study of high-temperature superconductors are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010192804471
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  • 5
    Electronic Resource
    Electronic Resource
    Thermogravimetric and Microgravimetric Studies of the Surface Properties of a High-temperature Superconductor (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 451-459 
    Details
    ISSN: 1572-8943
    Keywords: high-temperature superconductor ; surface properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper presents possible applications of thermal analysis, sorptomatic and microgravimetric methods for the study of surface adsorption and porosity properties via the programmed thermodesorption of liquid from the sample. The thermodesorption of liquids under quasi-isothermal conditions demonstrates that the adsorption layers on a high superconductor surface possess non-continuous properties. The degradation of the superconducting properties of an YBa2Cu3O7–δsuperconductor sintered in a CO2-containing atmosphere has been revealed. It is known that atmospheric contaminants such as CO2 and H2O can strongly influence the transition temperature, the critical current density, and the width of the superconducting transition of the YBCO superconductor. Similarly to other liquids adsorbed on solid samples, water induces changes in the physicochemical properties at the interface. A good correlation was obtained between the adsorption and porosimetric, thermal analysis and sorptometric findings. The results prove the applicability of these findings for determination of the adsorption capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010102618100
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